reqhttp is short for "request HTTP". HTTP is used to request data from web pages / web services.
"url" = The domain name or IP e.g. "cs2d.com"
"path" = The relative path of the thing you want to request, normally starting with a backslash. E.g. "/index.php"
mode = Controls how you want to receive the result. 0 for a plain string, 1 for a byte array (Lua table with numbers).
The requested data will be received with a delay. This is because it is sent over the network. You have to use the httpdata-hook to handle the incoming data!
The command will return a unique ID for the request. The same ID will be passed to the httpdata-hook so you can match request and response.
Attention: Many/big HTTP requests can influence the performance of the server in a negative way and can lead to ping spikes for connected players. Use with care!